Bespalova M, Behjatian A, Karedla N, Walker-Gibbons R, Krishnan M. Opto-Electrostatic Determination of Nucleic Acid Double-Helix Dimensions and the Structure of the Molecule–Solvent Interface.
Macromolecules 2022;
55:6200-6210. [PMID:
35910310 PMCID:
PMC9330769 DOI:
10.1021/acs.macromol.2c00657]
[Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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A DNA molecule is
highly electrically charged in solution. The
electrical potential at the molecular surface is known to vary strongly
with the local geometry of the double helix and plays a pivotal role
in DNA–protein interactions. Further out from the molecular
surface, the electrical field propagating into the surrounding electrolyte
bears fingerprints of the three-dimensional arrangement of the charged
atoms in the molecule. However, precise extraction of the structural
information encoded in the electrostatic “far field”
has remained experimentally challenging. Here, we report an optical
microscopy-based approach that detects the field distribution surrounding
a charged molecule in solution, revealing geometric features such
as the radius and the average rise per basepair of the double helix
with up to sub-Angstrom precision, comparable with traditional molecular
structure determination techniques like X-ray crystallography and
nuclear magnetic resonance. Moreover, measurement of the helical radius
furnishes an unprecedented view of both hydration and the arrangement
of cations at the molecule–solvent interface. We demonstrate
that a probe in the electrostatic far field delivers structural and
chemical information on macromolecules, opening up a new dimension
in the study of charged molecules and interfaces in solution.
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